Abstract

A new generation of cosmic microwave background (CMB) experiments will soon make sensitive high-resolution maps of the microwave sky. At angular scales less than ∼10′, most CMB anisotropies are generated at z < 1000, rather than at the surface of last scattering. Therefore, these maps potentially contain an enormous amount of information about the evolution of structure. Whereas spectral information can distinguish the thermal Sunyaev-Zeldovich effect from other anisotropies, the spectral form of anisotropies generated by the gravitational lensing and the kinetic Sunyaev-Zeldovich (kSZ) effects are identical. While spectrally identical, the statistical properties of these effects are different. We introduce a new real-space statistic, 〈θ(n̂)3θ(m̂)〉c, and show that it is identically zero for weakly lensed primary anisotropies and, therefore, allows a direct measurement of the kSZ effect. Measuring this statistic can offer a new tool for studying the reionization epoch. Models with the same optical depth, but different reionization histories, can differ by more than a factor of 3 in the amplitude of the kSZ-generated non-Gaussian signal. © 2007. The American Astronomical Society, All rights reserved.